Method of making insulated wire units



Oct. 17, 1944. R, J, AUST 2,360,312

METHOD 0F MAKING INSULATED WIRE UNITS Filed July 1o. 1941 INVENT OR.

ATTORNEY Patented Oct. 17, 1944 U 2,360,312 ivm'rnon or MAKING INSULATED wma UNrrs Robert -J. Aust, Indianapolislnd., assignor to P. R. Mallory Co., Inc., Indianapolis, Ind., a corporation of Delaware Appllcatlonlluly 10, 1941, Serial No. 401,725

Z Claims.

This invention relates to an insulated wire unit and method of making the same.

An object oi the invention is to improve insulated wire units and their method of manufacture.

Other objects of the invention will be apparent from the following description and accompanying drawing taken in connection with the appended claims.

The invention comprises the features of construction, combination of elements, arrangement of parts, and methods of manufacture and operation referred to above or which will be brought out and exemplified in the disclosure hereinafter set forth, including the illustrations in the drawing.

In the drawing: y

-Figure 1 illustrates a length of insulated wire -used in the manufacture of a wire unit of the present invention;

Figure 2 illustrates a step in the process of making the wire unit;

Figure 3 illustrates a modied method which may be substituted for that shown in Figure 2;

Figure 4 illustrates a unit in semi-completed condition; and

Figures 5 and 6 illustrate two types of wire units in completed condition.

In various, types of electrical apparatus it is necessary to use relatively short lengths of insulated wire to electrically connect various terminals of the apparatus. For example, in electromagnetic vibratory interrupters such ,as are used in power supply systems and radio receiving sets and the like relatively short lengths of braided copper wire insulated with a suitable insulating sleeve are needed to connect the electromagnet andthe various contact springs which are located inside a suitable can or container with terminals mounted in or projecting from one wall or end of the container.

In the past it has been customary to use a ilexible stranded or braided copper wire which was cut to the desired length, tinned at its ends and thencovered with a pre-cut length of rubber tublng for insulation purposes. This'arrangement has proved unsatisfactory in many cases due to the fact that relatively high operating temperatures are sometimes encountered in the vibrators and the rubber tubing is subjected to melting and to oxidation hardening in service resulting in insulation failures and other troubles. This method of making an insulatedlead Wire has'also l 'the fibres of sleeve Il.

or Woven nbre covering, the fibres of which are thermoplastic or thermoadhesive in nature.

While a preferred embodiment of the invention is described herein, it iscontemplated that considerable variation may be made in the method of procedure and the construction of parts without l departing from the spirit of the invention. In the following description and in the claims, parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit. Referring to the drawing, Figure l shows a length of stranded wire I0 covered with a braided sleeve Il of synthetic resin bres which can be softened and sealed by heat, such as cellulose acetate. Other fibres which may in some cases be used may be formed of nylon, vinyl resins and other materials which are heat fusible or heat softening. The covered wire used may be made of any lengthand may, for example, be taken from a reel as used.

In order to produce the sections of insulated wire desired, a heated instrument is .brought into contact with the insulated sleeve I I at spaced intervals along the length of the wire, the distance between the contact points corresponding to the length of insulating sleeve desired on the nished lead wire. As shown in Figure 2, for example, the wire is simply rolled along a heated rod or small heated soldering iron l2 which is at a temperature slightly above the softening temperature of The result of this procedure is to produce a bonded ring i3 around the wire at the point of contact with the heated inf strument, the iibres at this point sticking together due to the heating. As an alternative to the method shown in Figure 2, the covered wire l0 may be clamped -between a pair of heated jaws Il and I5 of a clamping device to produce a melted ring about the wire.

The wire is then cut into sections of the desired length, the cuts being made through the wire and covering at approximately the middle of the points of fusion' Figure 4 illustrates al length of wire which has been cut through the points of fusion leaving one uncut fused ring at an intermediate point. This fused portion is quite brittle and the sleeve can readily be broken at this point by simply bending the wire back and forth between the ngers a. few times thus separating the sleeve Il into two sections. One of the sections may then be slid off the wire leaving the length of wire l0 with a sleeve section I I covering part of its length only as shown in ,Figure 5. The sleeve Il, being quite elastic, may be impregnating the sleeve with a binder.

drawn back from the end of the wire leaving a bare end which can be attached to an electric terminal with or without tinning.

Where a bare section of wire is not required the wire may be cut as shown in Figure 6 at two fused points and the ends shoved back to expose free ends of the Wire.

The fused ends of the sleeve are bonded together by the fusion and hence do not tend to fray out, as is the case where no bonding is obtained. This fraying has heretofore prevented the use of wire having braided sleeves without However, impregnation has given the braided covering too great a stiffness for many applications and hence it has not heretofore been possible in such applications to use braided coverings. Also it was somewhat of a problem heretofore to cut a sleeve at an intermediate point so as to provide a bare wire section as shown in Figure 5 withoutI cutting 20 through the wire. The brittleness of the covering at the fused sections provided by the present invention permits the sleeve to be readily broken at this point without the use of cutting tools and therefore greatly simplifies th stripping of the wire.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is 1ntended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is: 1. The method of making insulated wire units then pushing said free ends of said sheaths back to expose the ends of said shorter lengths of wire.

2. The method of making an insulated wire unit from a length of wire insulated with a sheath formed of thermoplastic bres which comprises heating-said bres in a path around said sheath at an intermediate point along the length of said wire to coalesce said bres at said point and produce a brittle point in said sheath, and then breaking said sheath at said-brittle point and pushing the ends of said sheath thus formed back to expose a section of said wire.

' ROBERT J'. AUST., 

